Various different apparatus have heretofore been made for forming bag-type packages from strip web material. In some apparatus for forming bag-type packages such as disclosed in U.S. Pat. Nos. 2,918,769; 2,555,758 and 3,045,405, the package is formed around the product by depositing the product on the strip, infolding the strip to form a tube around the product, and thereafter transversely sealing the tube first at the lead and then at the trail end of the product. Such apparatus present some problems in controlling the position of the product in the strip after the product is deposited on the strip and until the strip is transversely sealed at the lead and trail sides of the product, and such apparatus are not adapted for packaging fluent materials. In the so-called vertical form-fill-seal machines, for example as disclosed in U.S. Pat. Nos. 4,067,173 and 4,288,965, the strip web material is formed into a tube as the lead end of the tube is advanced downwardly and the tube is transversely sealed at its lower lead end. Product is introduced into the upper end of the tube while it remains attached to the strip, and the tube is therafter transversely sealed and severed at the trail side of the product in the tube to separate a bag-type package from the strip. In such machines, filling of the bag occurs while the tube remains attached to the strip and this generally increases the overall cycle time since the time required to advance the sleeve and seal the sleeve is, at least in part, additive with respect to the fill time. Further, in such machines, the strip web material is formed into a downwardly extending tube by drawing the web material over a forming shoulder and this can produce stresses in the web which cause stretching and other degradation of the web material. In another type of apparatus for packaging products in strip web material, such as shown in U.S. Pat. Nos. 3,000,152; 3,579,948; and 3,952,480, the strip web material is formed into generally flattened bags that are thereafter reopened by a means such as an air blast, vacuum cups or plows external to the bag, for subsequent filling. However, problems are encountered in such machines in effecting reliable reopening of the mouth of the flattened bags.
An object of this invention is the provision of a method and apparatus for making bag-type packages from strip web material having an improved system for supporting and feeding the lead end portion of the strip and for forming a bag therein that is open at the lead end of the strip.
Another object of this invention is the provision of a method and apparatus for making bag-type packages from strip web material in which the lead end portion of the strip web material is advanced to a bag loading station and formed into a bag that is open at the lead end of the strip, and in which the open ended bag is separated from the strip at the bag loading station; transferred with its open end up to a filling station; and thereafter to a bag closing station so that filling of one bag and closing of a previously filled bag can be effected while still another bag is being formed and advanced to the bag loading station.
Various other objects of this invention are the provision of a method and apparatus for making bag-type packages from strip web material wherein the length of the bags can be readily varied; wherein the length of the bags can be correlated with printed indicia on the strips for registration of the printed indicia with the bag; in which degradation of the strip web material during formation of the bag is minimized; and which can be adapted for multi-lane operation to increase the package output of the packaging machines.
Accordingly, the present invention provides a method and apparatus for making bag-type packages from strip web material in which an elongated mandrel is moved lengthwise along a feed path in forward and return strokes, an end portion of strip web material is formed into a sleeve around the mandrel, the sleeve is advanced with its lead end forward along the feed path during at least a portion of the forward stroke of the mandrel to a forward position, the lead end of the sleeve is opened, the sleeve is transversely sealed at a location spaced inwardly of its lead end to form a bag in the sleeve that is open at the lead end of the sleeve, and the sleeve is severed at a location inwardly of the transverse seal to separate the bag from the sleeve and provide an unsealed lead end on the remaining portion of the sleeve.
Positive opening of the lead end of the sleeve is achieved by moving a forward end portion of the mandrel through the lead end of the sleeve and then retracting the forward end portion into the sleeve prior to transverse sealing of the sleeve.
Transfer of the bags from the bag loading station to the bag filling station and to the bag closing station is effected by a transfer mechanism having a plurality of gripper assemblies which are operated to grip the open end of the bag at the bag loading station; transfer the bag with its open end up to a bag filling station while holding the bag open; and thereafter transfer the bag from the bag filling station to a bag closing station.